There are forklifts having a hydraulic driving device referred to as a hydro static transmission (HST) provided between an engine as a driving source and driving wheels. The hydraulic driving device includes a variable displacement traveling hydraulic pump driven by the engine, and a variable displacement hydraulic motor driven by hydraulic oil discharged from the traveling hydraulic pump in a main hydraulic circuit as a closed circuit, and allows a vehicle to travel by transmitting driving of the hydraulic motor to the driving wheels.